Decorative lamp



FIG. 1 is a front view of decorative lamp showing my new design.

FIG. 2 is a rear view thereof;

FIG. 3 is a left side view thereof;

FIG. 4 is a right side view thereof;

FIG. 5 is a top plan view thereof;

FIG. 6 is a bottom plan view thereof; and,

FIG. 7 is an elevation view thereof. 

The ornamental design for “decorative lamp,” as shown and described herein. 